The present invention relates to a latch for use on the door of a refrigeration chamber or freezing chamber and, more particularly, to an unlatching device arranged for unlatching the door latch from the indoor side.
In the refrigeration chambers of walk-in type, it is essential from the view point of safety that anyone who has happened to be confined in the chamber due to a careless locking operation by another person or an accident can unlatch the latch to open the door by himself from the indoor side.
To cope with this demand, hitherto such a safety unlatching device has been used in which a threaded rod projected from the rear side of a latch support is extended through the frame wall of the chamber and a nut screwed to the inner projected end of the threaded rod. Anyone who is confined in the chamber can disengage the latch support from the latch of the latch device by pushing outwards the threaded rod to make the latch support move away from the outer surface of the chamber wall, after fully retracting the above-mentioned nut towards the inner end.
According to this arrangement, however, it is necessary to rotate the nut by a large number of turns to retract the nut to a position where it permits the disengagement of the latch support from the latch. In addition, a considerably large force is required to rotate the nut on the threaded rod because of icing on the threaded rod or nut. For these reasons, a long time is inevitably required for anyone accidentally confined in such a chamber to escape from the chamber.